let str = '123456789';
let str1 = str.substring(3,5)
console.log(str1)
let str2 = str.substr(3,5)
console.log(str2)
let str3 = str.slice(3,5)
console.log(str3)

let str4= str.substr(-3,6)
console.log(str4)

let k = `YbcxFTrNguWkGFB,叶会建专用网站,医疗健康,家庭医生,在线医疗咨询,,在线医疗咨询,在线医疗,在线医疗咨询电话,在线咨询医生,医生在线,私人医生,ceshi1,ceshi2,cehi43,65465`;
// console.log([...new Set(k.split(','))].indexOf(''))
// let uniqueArr = [...new Set(k.split(','))];
// console.log(uniqueArr)
// uniqueArr.splice(5,1)
// console.log(uniqueArr)
let kArr = [...new Set(k.split(','))];
console.log(kArr)
let ks=kArr.filter(item =>{
    return !(!item ||item==='')
})
console.log(ks.slice(0,13).join(','))